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1. What is the current flowing in a circuit if 30C are passed in 1

minute?

Q = It

30 = I x 60

I = 30/60

0.5A

answer

2. What voltage would be measured over a 100 Ω resistor when 10mA

flows through it?

V = IR

V = 0.01 x 100

1V

answer

3. How many joules of energy are transferred by a 60W bulb every second?

P = E/t

60 = E/1

E =60/1

60J

answer

4. Calculate the size of the current flowing in a 3kW mains operated appliance.

answer

13A

5. A television draws 0.1 A and has a resistance of 5000Ω. Calculate the

power consumption

P = IV

P = 0.1 x 5000

50W

answer

6. How many 1.5V bulbs operating at their correct voltage could be connected

in series with a 6V cell?

Vs = V1+ V2…6 = 1.5 +1.5 + 1.5 +1.5

6 = 4(1.5)Four bulbs

answer

7. What is the total resistance of a set of Christmas lights comprising of 30

individual 10Ω lamps in series?

Rt = R1+R2+…

Rt= 30(10)

3600 Ω or 3.6kΩ

answer

8. An electrical supply for a caravan delivers a total current of 2A to the fridge

and lighting circuits. If the lights use 0.25A, what is the operating current of the

fridge?

It = Ilights+Ifridge

2= 0.25 + Ifridge

I fridge = 2 - 0.25

1.75A

answer

9.What is the total resistance of three 90Ω resistors connected in

parallel?

1/Rt = 1/R1+1/R2+1/R3

1/Rt = 1/90+1/90+1/90

1/Rt = 3/90

Rt = 90/3

30 Ω

answer

10. Work out the enegy used in kWhr for a 2000 W electric heater which is used for 45 mins?

E = Pt

E= 2(kW)x 0.75(hr)

1.5kWhr

answer

11. How many joules are used if a tumble dryer uses 0.75 kWh?

750Whr750J/s(hr)750x3600

2700kJ or 2700000J

answer

12. Select the appropriate formula from your data book..

That shows the relationship between charge, current and time.

Q=It

answer

13. Select the appropriate formula from your data book..

That shows the relationship between voltage, current and resistance.

V = IR

answer

14. State Ohm’s Law.

V = IR

answer

15.

Rt = R1+R2+R3

answer

Select the appropriate formula from your data book..To calculate resistances in series.

16.

1/Rt= 1/R1 +1/R2 + 1/R3

answer

Select the appropriate formula from your data book..For combining resistors in parallel.

17. State the relationship between Energy and Power

P = E/t

answer